This invention relates to the field of electronic door locks. More particularly, this invention relates to a multiple reader stand-alone door lock system for securing a door.
It is known in the field of electronic door locks to use a stand-alone electrically controlled lock to secure the door to a door frame. Such locks typically employ a system that compares stored valid user codes to an access code which is entered by a person seeking entry to the secured area. Such access code systems have generally used a single code reader device, such as a keypad or a card reader, for receiving the access code.
Electrically controlled door locks have found acceptance in business and university settings. For example, a door lock system may secure a dormitory room. Each resident of the room is issued an individual valid access code for the particular lock that secures their room. For safety and maintenance reasons, it is also required that the security and maintenance departments be able to access the dormitory rooms. Therefore, personnel from these departments are issued access codes for the door locks. Due to the large number of secured doors at a university, it is generally required that a single universal code be available to the safety and maintenance personnel to permit entry to large blocks of secured doors. Consequently, unauthorized personnel can gain entry to a large number of secured areas if the universal code is compromised.
To better control and monitor access to the secured areas, it is generally preferred that the individual security and maintenance personnel each be assigned a unique universal code. As a consequence, an individual door lock system will unlock not only for residents of the dormitory room, but also for a large number of additional universal codes. The greater the number of valid codes for a particular doorway, the greater the possibility that random entry of access codes will release the lock. When a universal code has been compromised, all the doors within a block or on the system must be individually reprogrammed to delete the old universal code and enter a new universal code.